Custom SMTP

Connect any SMTP server to BooleanSMTP with host, port, encryption and authentication, choose where credentials live, and watch the raw SMTP handshake while troubleshooting.

Custom SMTP connects BooleanSMTP to any SMTP server: your host’s own mail server, a provider not listed elsewhere in Mailers, or an SMTP relay a provider issues you directly.

Before you begin

From your SMTP provider or host: a host, a port, whether it needs encryption, and, if it requires authentication, a username and password.

Add the connection

In your WordPress admin sidebar, go to BooleanSMTP → Mailers.
Click Add Connection and choose Custom SMTP.
Under Sender Settings, fill in From Email and From Name.
Under SMTP Server Credentials, fill in SMTP Host, Port (default 587), and Encryption Method: None, SSL, or TLS (default TLS). Auto TLS sits next to it, on by default; see the tip below.
Turn on Authentication if your server requires a login, then fill in Username and SMTP Password.
Choose Credential Storage: Database, WP Config, or Environment.
Click Register Connection.

The Custom SMTP connection form, with Host, Port, Encryption Method, Auto TLS and Authentication fields. — Custom SMTP connection form

Choose where credentials are stored

Credential Storage offers Database, WP Config, or Environment. Switching away from Database replaces the whole SMTP Server Credentials panel with a snippet naming every field below as a constant, not just the username and password:

define('BOOLEANSMTP_SMTP_HOST', 'mail.example.com');
define('BOOLEANSMTP_SMTP_PORT', 587);
define('BOOLEANSMTP_SMTP_ENCRYPTION', 'tls');
define('BOOLEANSMTP_SMTP_USERNAME', '...');
define('BOOLEANSMTP_SMTP_PASSWORD', '...');

As Environment, define the same names as OS environment variables instead of PHP constants. See Storing credentials in wp-config for the general naming rule.

Send a test email

Use Test Email in the sidebar to confirm the connection works: see Send a test email for the steps.

Common errors

“Connection timeout” or “Network error”: check your firewall allows outbound SMTP, try the other common port (465 for SSL, 587 for TLS), and check with your host for port restrictions.
“Authentication failed”: verify the username and password are correct; some providers require an app password rather than your normal account password.
A self-signed or internal certificate fails TLS verification: BooleanSMTP always verifies the server’s TLS certificate, and there’s currently no setting to turn that off. Install a valid certificate on the server, or only use Encryption Method: None over a trusted private network.
See the raw SMTP conversation for a failed send: turn on Test Email Activity Console (BooleanSMTP → Settings → Testing & Content), then send another Test Email; the full SMTP handshake for that send appears right on the page.